An interesting post at BlenderArtists.org. I'm taking a look at the .blend file he posted.
Blender's Orientation Matrix. A tutorial from Luma Labs.
"Royalty free" blender models for game dev:
Blender Hotkey PDF. This is meant for version 2.36, but remains mostly relevant.
A dev named Shatter posted a very basic example of a gravity gun using a ray sensor
On BlenderArtist.org forums a couple years back. I LOVE very basic stuff. It's the easiest way to learn for sure. Just scroll down a bit and look for where he writes:
Here it is!
sorry it took so long, havent been on
Still worked in my 2.49: